T. Mori et al., Photoinduced electron transfer oxidation of alpha-methylstyrene with molecular oxygen sensitized by dimethoxybenzenes: a non-singlet-oxygen mechanism, TETRAHEDR L, 42(13), 2001, pp. 2505-2508
alpha -Methylstyrene (1) was photooxidized with oxygen in the presence of a
series of alkylated dimethoxybenzenes as a sensitizer in acetonitrile, aff
ording the cleaved ketone (2), epoxide (3) as well as a small amount of the
ene product (4) in ca. 1:1:0.04 ratio. A non-singlet-oxygen mechanism is p
roposed, in which an excited sensitizer is quenched by oxygen to produce a
sensitizer radical cation and a superoxide ion (O-2(.-)), the former of whi
ch oxidizes 1, while O-2(.-) reacts with the resulting 1(.+) to give the ma
jor oxidation products. (C) 2001 Elsevier Science Ltd. All rights reserved.